m. chergui - elettra...side chain motion probed by uv resonance raman of amino-acid residues: 2-10...
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M. Chergui
Perspectives for Time-Resolved UV to X-ray studies
at Synchrotrons
Wish list for (bio)chemical dynamics
• Element-selectivity
• Electronic structure
• Spin structure
• Geometric structure
• Time scales: ≥ 20 fs to 100s ps
• Condensed phase media (liquid, interfaces, amorphous, etc.)
The Science determines which tool to use!
0.01 0.1 1 10 100 keV
High Harmonic
Generation (≥As)
Synchrotron Radiation (≥ 50 ps)
X-ray Free electron
Lasers (≥50 fs)
XUV Free electron
Lasers (≥50 fs)
Plasma-based sources (≥50 fs)
Sources of short-wavelength pulses
Stability
Tuneability
Average flux
Protein Dynamics in Solution – From the Chromophore to the Scaffold
Spin dynamics
(singlet to quintet)
• intramolecular ET
(ring to metal, metal to
ring)
• Intramolecular
vibrational
redistribution (IVR)
• Electronic
relaxation: internal
conversion
• Structural dynamics
• Ligand dissociation
• Doming
• Cooling
10 fs ... 10 ps 10 ps … 100 ps
• Dielectric response of
amino-acid residues
• Cooling and heat transfer
• Helix motion
• Conformational changes
• Correlated motions
• Role of biological water
• intermolecular ET
ps ... ms > ms 1 ps ... 10 ps
• Cooperativity
• Allostery
• Signaling
• Respiration
X-ray spectroscopy (XAS, XES)
X-ray protein scattering
Deep-UV Circular Dichroism
SA
MP
LE
IT I0
Core-level spectroscopies
photoelectron
K
L
M
X-ray
Kb
Ka
L
M
Continuum
K
X-ray absorption Electronic structure Local geometry
X-ray emission Electronic structure Spin state
L
M
K
Photoelectron
Kinetic energy
Photoelectrons Binding energies Chemical bond
Continuum
XANES, NEXAFS, EXAFS, SEXAFS, XES, RIXS, ESCA, UPS, XPS, etc.
Fe
X
Planar ligated
(low spin)
Domed deoxy
(unligated, high
spin)
Fundamental processes in respiration
Local probing: XAS transients of Myoglobin-NO in a physiological solution with 70 ps resolution
Fe K-edge spectra (Lima et al, PCCP 2014)
Silatani et al, PNAS (2015)
~200 ps, 80% > 1 ns, 20%
Kinetic trace at 7.125 keV
- Biosystems are robust ! - Opens opportunities for Fs/ps solution XRS, XES, RIXS, etc.
- Slow kinetics (ca. 200 ps) due to recombination from remote NO’s - Domed ligated form populated in ~200 ps and decays in ~ 30 ps. - XFEL experiments to probe the short time components
Femtosecond X-ray absorption studies (Coll. SACLA)
Time trace at edge
Time constants: ~1, ~30, ~200 ps
Time trace at edge (electronic) Time trace at post-edge (structural)
~70 fs
~130 fs Pulse-limited rise
High-spin Low-spin
High-spin
High-spin
High-spin
Electronic response and
loss of NO ~70 fs
Structural response: Planar-to-
domed
~ 130 fs
Geminate recombination
~ 1-10 ps
Non-Geminate recombination
~ 230 ps
Domed ligated to planar structural
response ~ 30 ps
Proposed photocycle
Side chain motion Probed by UV resonance Raman of amino-acid residues: 2-10 ps (Sato et al, PNAS 104 (2007) 9627–9632)
Levantino et al, Nat. Comm. 2015: solution small-angle scattering (SAXS) Poor spatial resolution
Baerends et al, Science 2015: Serial crystallography studies, non-physiological
Environment response
Deep-UV Circular Dichroism
240 280 260 300 320 Wavelength [nm]
Exti
nct
ion
co
eff.
(x1
03
M-1
l
cm-1
)
0
2
4
6 Tyr
Phe
Trp
Biology: Amino acid residues and nucleotides
2D deep-UV set-up @ (Auböck et al, RSI 2012; Opt. Letters 2012)
Chemistry: Small molecules
Materials science: Transition Metal oxides e-
VB
CB
>3 eV
Auböck & Chergui, Nature Chem. (2015) Reinhard et al, JACS (2017) Monni et al, CPL (2017); PNAS (2018)
Consani et al, Science (2013) Monni et al, PNAS (2015)
Baldini et al, Nature Comm. (2017); JACS (2017); ACS Photonics (2018); NanoLetters (2018);Nature Phys. (under review)
CIRCULAR DICHROISM
Bottom figures: en.wikipedia.org
The absorption difference of left- and right-circularly polarized light:
CD transitions are associated with helical charge displacements in chiral systems:
Achiral coronene Chiral M-[6]helicene Chiral P-[6]helicene
Left-handed circular polarization
Right-handed circular polarization
ELECTRONIC CD FROM COUPLED CHROMOPHORES
Figures adapted from: Berova et. al, Chem. Soc. Rev. 36, 914 (2007)
Excitonically coupled chromophores:
Circular Dichroism:
Linear absorption:
CD probes the geometry of chiral systems of excitonically coupled chromophores!
ULTRAFAST CD SETUP
Liquid jet design: Picchiotti et al., Rev. Sci. Instruments 86, 093105 (2015)
Performance of static CD acquisition:
• Good agreement with commercial spectrometer
• Baseline deviations < 0.5 mOD in racemic mix
• Minimization of polarization artefacts via polarization scrambling
STATIC CD PERFORMANCE
Racemic mix
Λ-Enantiomer
Δ-Enantiomer
[Ru(bpy)3]2+
Probe
1.0 mM aqueous solution
ULTRAFAST CD SETUP
K. Kalyanasundaram, Coord. Chem. Rev. 46, 159 (1982)
TRANSIENT CD PERFORMANCE
[Ru(bpy)3]2+
Probe Pump
e-
0.3 mM aqueous solution, estimated peak fluence: 2 mJ cm-2
Racemic mix
Λ-Enantiomer
Δ-Enantiomer
Performance of transient CD acquisition:
• Baseline deviations < 0.02 mOD in racemic mix
• Precision < 0.1 mOD can be reached routinely in < 15 min of DAQ time
• The TRCD spectra of the two enantiomers display an excellent symmetry
Oppermann et al, Optica (in press)
S.M. Kelly et al. / Biochimica et Biophysica Acta 1751 (2005) 119– 139
Near-UV CD of dehydroquinase
Deep-UV CD of amino-acid residues and helices
Deep-UV CD of secondary structures
a-helix
b-sheets
Synchrotrons
Stability
Tune-ability
Flux
Time-resolution
Compatible with UV res. Raman
Extension to the X-ray domain
Non-photoinduced biological functions: Laser T-jump
Ashihara et al, JPCA 2007 Ma et al, PNAS 2008
Open scientific questions: electron transfer in heme Proteins (hemoglobin, myoglobin, cytochromes, etc.)
Trp7
Trp14
Haem
His93
FRET
Electron Transfer (QY~40%)
Deep-UV to visible transient absorption: Consani et al, Science (2013) Monni et al, PNAS (2015); JACS (submitted)
~20 ps
~120 ps
X-ray experiments with 1-10 ps resolution
Open scientific questions: intramolecular electron transfer and solvation dynamics
Cannizzo et al, JACS 2008 El Nahhas et al, JPCA 2010 El Nahhas et al, Inorg. Chem. 2011 El Nahhas et al, JPCA 2013
X=I, Br, Cl
Delayed electron transfer, two-centre electron transfer? Change of transition dipole due to solvation?
X-ray experiments with 1-10 ps resolution
Charge carrier trapping
in transition metal oxides
Penfold et al, Nature Comm. (2018)
CH3NH3PbI3
Cs+
Pb2+
Br/Cl-
Santomauro et al, Struct. Dyn. (2017)
Charge carrier dynamics
in perovskites
Electronic solvation dynamics
Pham et al, JACS (2007); JACS (2011)
“Dark” states in chemical
dynamics
Monni et al, PNAS (2018)
Doubly charged
O vacancy
G. Auböck, E. Baldini, C. Bacelar, Th. Barillot, B. Bauer, J. Budarz, O. Cannelli, G. Capano, R. Ingle, A. Lübcke, D. Kinschel, G. Mancini, F. van Mourik, M. Oppermann, Th. Penfold, S. Polishchuk, M. Puppin, H. Rittmann-Frank, J. Rittmann, Th. Rossi, F. Santomauro, B. Sorokin, L. Wang, Y. Zhao
S. Johnson, S. O. Mariager
P. Beaud, C. Borca, D. Grolimund, G. Ingold, J. A. Johnson, C. J. Milne
Jan Helbing
F. Lima, D. Khakhulin, W. Gawelda, P. Zalden, S. Schulz, Ch. Bressler
T. Katayama M. Yabashi
Optical Pump/X-ray probe experiments
M. Chergui, Acta Crystal. (2010); ARPC (2010); Comprehensive Biophysics (2012)
Measured signal = excited minus unexcited sample transmission at MHz rep rates
X-RayDetector
UHV
Sample(Liquid Jet)
From Storage Ring
X-Ray ProbeGe(111)Mono
Methods available with table-top systems
Soft X-ray absorption spectroscopy
Photoelectron spectroscopy
TOF
Nozzle
Catcher
Ekimova et al, Struct. Dyn. 2015 Galinis et al, Rev. Scient. Instr. 2017 Koralek et al, Nature Comm. 2018
Faubel and Winter, Chem. Rev. 2006 Abel, Faubel et al, Appl Phys A 2009 Ojeda et al, PCCP 2017
Issue with neighbour absorption edges
Jiang et al, JPCC 2014
Charge carrier dynamics in Spinel Cobalt oxide (Co3O4)
Fs non-resonant XES with hard X-rays
What can we do "only" at X-ray Free Electron Lasers?
• Ultrafast photon-in/photon-out experiments: Non-res. XES, RIXS, X-ray Raman, etc. • Non-linear X-ray optics: Multiphoton absorption, SHG, 4W-mixing, Transient Gratings, 2D X-ray spectroscopy
d8-d8 complexes: PtPOP
PtPOP = Tetrakis(μ-diphosphito(2-)-P,P’)diplatinate(II)
Crosby et al, Gray et al, etc. R.M. van der Veen et al., Ang. Chem. IE (2009); PCCP (2010); J. Am. Chem. Soc. (2011)
Monni et al., Nature Chem. (under review)
0 2000 4000
Time (fs)
Singlet ESA
Triplet ESA
Singlet SE
• Coherence transfer from S to T
• ISC time is 0.7 ps • Pure Dephasing
Time= 2 ps • Solvent dependent
ISC
Pt-Pt bond distance
En
erg
y
T1
S0
S1
ISC
Monni et al., PNAS (2018) QM/MM simulations (Coll. I. Tavernelli)
Baerends et al, Science 2015: SFX studies
Protein dynamics: Myoglobin-CO
Levantino et al, Nat. Comm. 2015: solution small-angle scattering (SAXS)
Levantino et al, Struct. Dyn. 2015: fixed energy fs XAS
Sension et al, in progress: polarized fs-XANES on Vitamin B12
Time-resolved core-level spectroscopies
ARPES
ESCA
UPS-XPS of liquids
Resonant X-ray
emission
Non-resonant X-ray emission
X-ray absorption
Resonant inelastic X-ray scattering
Non-linear X-ray optics
Multidimensional X-ray spectr.
Electron transfer
Spin cross-over
Charge carrier dynamics
Solvation dynamics
Bond forming and breaking
Photosynthesis
Surface dynamics
Interface dynamics
Lattice dynamics
Charge carrier dynamics
Defects
Protein Dynamics
Photocatalysis
Electrochemistry
Molecular Magnetism
Superconductivity
Strongly correlated materials
Nanoparticles
Solar energy conversion
UPS
XPS
Chirality
Fe
X
Planar ligated
(low spin)
Domed deoxy
(unligated, high
spin)
3. Biology: Fundamental processes in respiration
Mills et al, Science 1984
ELECTRONIC CD SPECTROSCOPY
Figures: Ranjbar and Gill, Chem. Biol. Drug Des. 74, 101 (2009)
Key features:
• Non-empirical structural probe
• Requires chiral, coupled chromophore assemblies
• Applicable to liquid-phase samples
• All-optical technique: ideal for femtosecond pulses
Applications:
•Global structure determination
•Stability via melting curves
•Ligand binding via induced CD
•Local chromophore interactions
XES Kα and XAS edge time traces match, but ~1 ps component is stronger in XES Kα
Kβ: sensitive to spin state
Femtosecond X-ray emission studies
Steady state and transient Kα XES Steady state and transient Kb XES
attoseconds
10-18
s
femtoseconds
10-15
s
picoseconds
10-12
s
nanoseconds
10-9
s
microseconds
10-6
s
milliseconds
10-3
s
electron motion
core-hole lifetimes
motion of nuclei
molecular vibrations
optical phonons
molecular bond formation
rotation of molecules
molecular librations
Acoustic phonons
vibrational dephasing
electronic relaxation
fluorescence
thermal effects
large-scale protein motion
phosphorescence
protein folding
chemical kinetics
110 as delay between
electron emission
from conduction
band and lower-lying
states in Tungsten
upon irradiation
The Fe K-edge core-
hole lifetime is 4 fs
period of the
symmetric stretch
in H2O is 10 fs
< 200 fs
Hemoglobin R->T
transition takes
microseconds
Camera
shutter speeds
range from ms
through to
seconds
Lasers
Electronics (Flash Photolysis)
high-harmonic generation
Eigen-Porter-Norrish 1967
Zewail 1999
Significant time scales
Monni et al., Chem. Phys. Lett. (2017)
Violation of the Kasha-Vavilov rule!
Pt-Pt bond distance
En
erg
y
1A2u
3A2u
1A2g
<100 fs
The blind men and the elephant (Jain, Buddhist, Sufi and Hindu lore)
One single experience can be true, but it is inherently limited
by its failure to account for other truths or a totality of truth
Catalysis and solar energy conversion with Metal Oxides
Photocatalysis Fujishima, Honda (1972)
Solar energy Grätzel, O’Regan (1991)
3.2 eV
- Charges at surfaces - Long time trapping
- Long range transport - High mobility: no trapping
Static
Bare,
100 ps, Exc. 355 nm
Ti K edge spectra
Ti4+Ti3+
Ti4+Ti3+
N719 dye-sensitized,
100 ps, Exc. 532 nm
Ps-studies: Rittmann-Frank et al, Ang. Chem. Int. Ed (2014)
-1 eV-shifted amorphous minus anatase spectrum
Rittmann-Frank et al, Ang. Chem. Int. Ed. (2014) Buddarz et al, Chimia (2017)
core
Defect-rich shell
Electron trapping occurs at pentacoordinated defects Bulk case: trapping deep inside surface shell Injection: trapping on the outer surface Similar results obtained for Rutile TiO2
Femtosecond X-ray absorption studies of electron trapping
Time scan @ 4.980 keV Electron trapping time <200 fs
Santomauro et al, Scient. Rep. (2015)
Structural ~330 fs Electronic ~100 fs
Obara et al, Struct. Dyn. (2017)
Hole trapping site at singly charged Oxygen vacancies in ZnO
Bulk ZnO
structure
Doubly charged
O vacancy
Hole trapping sites are native singly-
charge oxygen defects
EXAFS
XANES
VO+ + h+ → VO
++
Expansion of the 4 neighbouring
Zn atoms by ~20%
Strong signature in transient X-
ray spectra
Hole trap is final state of green
luminescence
Hole trapping occurs in approx.
1.2 ps
Penfold et al, Nature Comm. (2018)
Ligand recombination in
hemoproteins
Silatani et al, PNAS (2015)
CH3NH3PbI3
Cs+
Pb2+
Br/Cl-
Santomauro et al, Struct. Dyn. (2017)
Charge carrier dynamics
in perovskites
Electronic solvation dynamics
Pham et al, JACS (2007); JACS (2011)
Solution chemical dynamics
Reinhard et al, Struct. Dyn. (2014)
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